Question

1. The two genera, Bacillus and Clostridium, are similar in that both are

a. catalase positive.

b. strict anaerobes.

c. spore formers.

d. strict pathogens.

ANSWER:

(Level 1, Objective 1)

2. A physician suspects her patient has erysipeloid. She calls the laboratory for help with specimen selection and collection. You recommend she collect a

a. swab of infected skin surface.

b. nasopharyngeal swab.

c. swab of sinus tract drainage.

d. full thickness biopsy.

ANSWER:

(Level 1, Objective 2)

3. To diagnose diphtheria, the appropriate specimen for collection is a

a. pharyngeal swab.

b. portion of the membrane.

c. portion of the black scab.

d. swab of the contaminated medical device.

ANSWER:

(Level 1, Objective 2)

4. Loeffler’s medium is useful in making a presumptive identification of Corynebacterium diphtheriae from a pharyngeal culture because it

a. inhibits the growth of normal upper respiratory flora.

b. detects hydrogen sulfide production.

c. enhances metachromatic granule formation.

d. detects toxin-producing strains.

ANSWER:

(Level 1, Objective 3)

5. Overlaying an agar plate with sterile olive oil ensures adequate growth of

a. Erysipelothrix rhusiopathiae.

b. Arcanobacterium haemolyticum.

c. Lactobacillus spp.

d. Corynebacterium urealyticum.

ANSWER:

(Level 1, Objective 3)

6. The breakdown of casein, tyrosine, and xanthine is used in differentiating ____________ spp.

a. Nocardia

b. Streptomyces

c. Actinomyces

d. Corynebacterium

ANSWER:

(Level 1, Objective 4)

7. A positive reaction for the inverse CAMP test appears as an arrowhead of

a. non-hemolysis for Arcanobacterium haemolyticum when tested against Group B Streptococcus.

b. non-hemolysis for Corynebacterium ulcerans when tested against Staphylococcus aureus.

c. enhanced hemolysis for Arcanobacterium haemolyticum when tested against Group B Streptococcus.

d. enhanced hemolysis for Corynebacterium ulcerans when tested against Staphylococcus aureus.

ANSWER:

(Level 2, Objective 4)

8. Nocardia, Actinomyces, and Streptomyces spp. microscopically appear as

a. palisading, clubbed, gram-positive rods.

b. gram-variable rods.

c. branching gram-positive rods.

d. long, thin, gram-positive rods.

ANSWER:

(Level 1, Objective 5)

9. Lactobacillus spp. typically produce colonies that are

a. white and chalky.

b. large, dry, and beta-hemolytic.

c. gray-white, translucent. with subtle beta-hemolysis.

d. pinpoint and alpha-hemolytic.

ANSWER:

(Level 1, Objective 5)

11. The only catalase-negative, gram-positive rod capable of producing hydrogen sulfide is also

a. intrinsically vancomycin resistant.

b. esculin positive.

c. motile.

d. gelatinase positive.

ANSWER:

(Level 2, Objectives 5 and 6)

12. A pinpoint, gray-white colony is isolated as >100,000 colonies/mL from the urine of an 89-year-old leukemic patient. The colony stains as palisading gram-positive rods. The organism should be

a. catalase negative and urea positive.

b. catalase positive and urea positive.

c. catalase negative and urea negative.

d. catalase positive and urea negative.

ANSWER:

(Level 2, Objective 6)

13. The gram-positive rod that produces an umbrella motility pattern in semisolid medium is also

a. catalase positive.

b. esculin negative.

c. non-hemolytic.

d. sodium hippurate negative.

ANSWER:

(Level 2, Objective 6)

14. The colonies of Streptococcus agalactiae and Listeria monocytogenes are nearly identical. The two organisms can be differentiated by the

a. sodium hippurate hydrolysis test.

b. CAMP factor test.

c. catalase test.

d. diseases they cause.

ANSWER:

(Level 1, Objective 7)

15. A 20-year-old female presents with pharyngitis. The rapid group A Streptococcus screen is negative, and a blood agar plate is inoculated. After 24 hours incubation, a tiny gray colony with a narrow zone of beta-hemolysis is observed. The microbiologist performs a streptococcal serotype for group A and the result is negative. She should

a. perform a Gram stain and catalase test.

b. finalize the culture as “No Group A Streptococcus isolated.”

c. repeat the streptococcal serotype after boiling the organism suspension.

d. perform an ELEK test.

ANSWER:

(Level 2, Objective 7)

17. Which of the following organisms is not considered pathogenic until it has been infected by a bacteriophage?

a. Bacillus anthracis

b. Corynebacterium pseudotuberculosis

c. C. diphtheriae

d. Actinomyces israelii

ANSWER:

(Level 1, Objective 9)

19. The modified ELEK test is used to

a. detect the metachromatic granules of Corynebacterium diphtheriae.

b. identify C. diphtheriae.

c. detect toxin-producing strains of C. diphtheriae.

d. differentiate C. jeikeium and C. urealyticum.

ANSWER:

(Level 1, Objective 9)

20. A leg wound from a 15-year-old male football player yields:

Heavy growth of Staphylococcus aureus

Light growth of Staphylococcus not S. aureus

Light growth of Diphtheroids

Light growth of viridians Streptococcus

The microbiologist should

a. report the Staphylococcus aureus and call the other organisms normal skin flora.

b. report each of the organisms isolated individually.

c. perform further testing on the diphtheroids.

d. report all four organisms as normal skin flora.

ANSWER:

(Level 2, Objective 10)

21. Individuals infected with toxigenic Corynebacterium diphtheriae must be treated with

a. penicillin.

b. DPT vaccine.

c. antitoxin.

d. a and c.

e. b and c.

ANSWER:

(Level 1, Objective 11)

22 A gray-white colony displaying subtle beta-hemolysis is isolated from a cerebrospinal fluid. The organism is a gram-positive rod that is catalase positive, motile at room temperature, and esculin positive. Which patient history is most likely associated with this culture?

a. 45-year-old female weaver

b. 2-day-old infant male delivered at 32 weeks gestation

c. 33-year-old female with recent dental surgery

d. 58-year-old cattle farmer

ANSWER:

(Level 2, Objective 12)